Streptomycin is very stable when kept dry and away from light. However, it will break down in light. If your zip-lock bag was clear plastic and located on a windowsill, the product may have degraded at least to some extent. Otherwise, it should be OK.
On Feb 21, 2013, at 2:55 PM, Rye Hefley <ducn...@yahoo.com<mailto:ducn...@yahoo.com>> wrote: Hello, I have a pouch left over that I purchased last year that was never opened. There is no expiration date on the pouch. I also have a pouch that I purchased and opened last year. The unused powder remained in the pouch in a zip-lock bag. The only thing I could find is on the label, "Keep tightly closed. Store at cool temperature when possible and with minimum exposure to the atmosphere." I have kept the zip-lock tightly closed with minimum air inside. Storage temperature for both (open/unopened) packages varied from about 60 - 85 degrees F. I found this site: http://extension.missouri.edu/p/G1921 that has some general guidelines for wettable powders: "Moisture is the greatest factor affecting their storage, as it can cause caking that may reduce the effectiveness of the pesticide. " So that tells me as long as there is no caking both (open/unopened) should be still good. Is that true? Your wisdom is appreciated. Thanks, Rye Hefley So. Cal. _______________________________________________ apple-crop mailing list apple-crop@virtualorchard.net<mailto:apple-crop@virtualorchard.net> http://virtualorchard.net/mailman/listinfo/apple-crop ************************************************************** Dave Rosenberger, Professor of Plant Pathology Cornell University's Hudson Valley Lab P.O. Box 727, Highland, NY 12528 Office: 845-691-7231 Fax: 845-691-2719 Cell: 845-594-3060 http://www.nysaes.cornell.edu/pp/faculty/rosenberger/
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